The present invention relates to an improved plastic shuttlecock for use in a badminton game.
In general, a conventional shuttlcock is made up of a plurality of natural feathers which are bound together piece by piece by adhesive glue and threads. It takes a lot of labor and time to produce a shuttlecock of good quality for use in a formal game. First, feathers meeting certain standards must be sorted out by way of manual labor and then are pieced together by adhesive glue and threads into a cone shape; at the end, a cork cap is attached to the topmost end thereof. Such a natural shuttlecock is easily damaged when it is hit not on the cork cap but on flight feathers with force.
It is relatively expensive to produce such a natural shuttlecock because of involvement of too much manual labor and time.
To make a shuttlecock more durable, plastic shuttlecocks have been designed and developed for many years. Over those years, some kinds of high quality plastic shuttlecocks having good controllability, flying stability and satisfactory feeling of stroke are available in sporting markets.
It seems an increasing trend for badminton players to substitute feather shuttlecocks with plastic ones in routine practices. However, there are still some problems associated with such a prior art plastic shuttlecock in design, which make a conventional plastic shuttlecock unable to perfectly conform to aerodynamic requirements given as below:
1. At the end of each flight journey i.e., as horizontal speed becomes zero, a shuttlecock must be dropped as vertically as possible. PA0 2. A shuttlecock itself must not swing to and fro in flight. PA0 3. The flight direction must conform to the hitting direction. PA0 1. The structural strength of a prior art collar tube is not satisfactory. PA0 2. A shuttlecock will be seriously deformed at the corrugated tail portion into an elliptic form as a result of minor improper fitting of the cork cap to a collar tube. PA0 3. A cork cap will be easily separated from the collar tube after a certain number of hittings because of the securing flanges on a collar tube can not hold a cork cap firmly in place, resulting in shortening of operation time of a shuttlecock. PA0 4. The improvement of the strength of a collar tube by increasing the wall thickness thereof results in an increase of weight at the front end of a shuttlecock, reducing the flying speed thereof. PA0 5. When adhesive glue is evenly dispensed all over a collar tube and the securing flanges, fixing of a cork cap onto the collar tube will easily push the adhesive glue to one end of the cap, making the other part of the cap lack of adhesive glue. That causes a cork cap to be easily separated from a shuttlecock when hit a certain number of times. PA0 6. Lack of strength of a collar tube generally results in deformation at the corrugated skirt of a shuttlecock when a cork cap is forced into engagement therewith, seriously effecting the flying features of a shuttlecock.
As shown in FIG. 1, a conventional plastic shuttlecock has offered the design of lower skirt undulation which had two different ratios of surfaces formed by the undulation with the surfaces trellised in different densities so as to offer the effect of rotation during the flight. The design of tail skirt undulation has been prevailing among the plastic shuttlecocks giving them increasing flight stablility, and also offering the necessary means for preventing them from swinging to and fro during flight. However, the lower skirt of a plastic moulded shuttlecock, which is handicapped by the weight distribution and the tail skirt undulation being supported by the very thin stems, used to be deformed and shrunk by air pressure when it was hit by a racket. Then, the projection area of the lower skirt was decreased, and the radius of counter-rotation (owing to the air resistant area being decreased) was increased. Thus, the problems of accuracy of stroke, stability of counter-stroke and control should be improved accordingly. Furthermore, the design of the air resistant area of the lower skirt undulation have not permitted improvement of the exhaust air stream by opening larger air stream outlets therein owing to its weak structure. However, the difference of air sucking pressure between inner and outer sides of the lower skirt can not be lowered, thus improved flight stability of a shuttlecock can not be obtained.
Furthermore, the collar tube of a cork cap of a prior art plastic shuttlecock has the following disadvantages: